The present invention relates generally to mounting structures of fixed or hard disk assembly (xe2x80x9cHDAxe2x80x9d) for use with magnetic disk drive units, and more particularly to a cable layout technique therefor.
Magnetic disk drives have been widely employed as external data storage units of modern computers. When magnetic disk drives are used in the form of unitary components, a single magnetic disk drive is accommodated within the interior of a personal computer as its storage module for example (as a logical equipment drive xe2x80x9cCxe2x80x9d in most cases). The same goes with other cases where it is used as a storage device adaptable for use in copying machines, land vehicle travel route guidance systems also known as xe2x80x9ccar navigation systems,xe2x80x9d portable or xe2x80x9cmobilexe2x80x9d computers, electronic cameras, and other electronic devices.
On the contrary, large size computers, called main frames, are designed to employ external storage apparatus including redundant arrays of inexpensive disk (RAID) systems with a plurality of magnetic disk drives packed in a box-like housing and/or large-capacity magnetic disk devices. These magnetic disk devices (such as RAIDs and mass-storage disk devices) will be collectively called the magnetic disk devices of the broad sense hereafter in the description. One typical approach to mounting for installation such magnetic disk devices of broad sense is to settle around a unitary magnetic disk drive (magnetic disk device of the narrow sense or alternatively HDA) a vibration-absorptive or anti-vibration support mechanism capable of withstanding vibration and shocks as externally applied thereto.
An HDA support structure for exclusive use in RAID systems or mass-storage magnetic disk devices is disclosed in JP-A-8-161880 (and its corresponding U.S. Pat. No. 5,740,011) under the name of the same applicant. Typically a magnetic disk device of the narrow or strict sense, HDA, is structured from two major parts: a mechanical part including magnetic disk storage media and more than one magnetic read/write head (referred to as a head/disk assembly or simply xe2x80x9cH/DAxe2x80x9d hereinafter), and electronic circuitry part (referred to hereafter as electronic control circuit board) for use in controlling the mechanical part.
A standard H/DA is designed to include an arm that is swingably movable with a pivot as its center, a magnetic head provided at the distal end of such arm, a rotatable magnetic disk media, an actuator for positioning the magnetic head at a desired location over the magnetic disk media, and an enclosure housing with its sealed interior space in which the above components are disposed. And, the H/DA is secured via a support mechanism to a fixed frame or fixation section of substantially rectangular shape (so-called drive bay within an upper-level device in the case of the magnetic disk device of the narrow sense).
Further, since the H/DA is designed so that its arm""s center of gravity is identical in position to a layout position of the pivot, any vibration and shocks as externally applied thereto to give the H/DA translational movement will no longer serve as disturbance with respect to position determination of the magnetic head involved. However, such vibration/shock application can result in occurrence of disturbance relative to magnetic head positioning in cases where moment components about the magnetic disk media""s rotary shaft and actuator""s rotation axis are included in such vibration or the like. It is thus required that the support mechanism for rigidly attaching the H/DA to its associative fixed frame is free from the risk of disturbance with respect to the positioning procedures of the magnetic head within the H/DA upon externally applying of vibration that would result in the fixed frame exhibiting translational motion. More precisely, it should be required that the position of the gravity center of the HDA be taken into consideration when attaching to the fixed frame the HDA including both the H/DA and the electronic control circuit board operatively associated therewith. Note here that the HDA""s gravity center position and the H/DA""s gravity center position may be substantially the same as each other in intended meaning and definition, depending on the mass of the electronic control circuit board.
On the other hand, it is deemed convenient to employ commercially available general purpose products or xe2x80x9cafter-marketxe2x80x9d items as the magnetic disk devices of narrow sense when mounting them into electronic equipment of interest. In addition, if it is permissible to employ HDAs of after-market items for RAIDs or large-size mass-storage disk devices, then production costs decrease in the resultant systems. Here, the HDAs of after-market items may refer to those magnetic disk drives of the form factor type with adaptability to several kinds of interface standards such as the integrated drive electronics (IDE), enhanced IDE (EIDE), small computer system interface (SCSI) and others, including but not limited to 3.5-inch type, 2.5-inch type, 1.8-inch type, and so forth. Also note that an after-market HDA product is provided with an electronic control circuit board operatively associated with the H/DA, which is connected to upper-level apparatus via a cable and a connector placed at an end portion of the H/DA.
While the prior art structure as taught by the above-identified Japanese document JP-A-8-161880 employs its special-purpose or xe2x80x9cdedicatedxe2x80x9d HDA, it has been found by the inventors as named herein that an attempt to replace this dedicated HDA with a mere general purpose HDA of after-market item can result in occurrence of inconvenience. More specifically, in view of the fact that the dedicated HDA comes with its own electronic circuitry as internally built therein, a specially designed cable wiring structure of the exclusive use type is used for transferring electrical signals from the H/DA to the electronic control circuit boardxe2x80x94in this case, such wiring structure did not affect in any way the behavior of an actuator as internally disposed in the H/DA. However, when an attempt is made to apply an HDA of after-market item in place of the dedicated HDA to a fixed frame that has been used for mounting of the dedicated HDA, extra cable wiring/routing schemes are required due to the necessity of separately converting the signals from the after-market HDA product into appropriate signals suitable for use therein. Another problem faced with the prior art lies in an inability to provide any sufficient spatial margins for accommodation of the support mechanism that is used to increase stiffness or robustness against vibration and/or shocks occurring due to rotation of the H/DA. Letting the fixed frame decrease in thickness in a way suited for the size of an HDA of after-market item would result in occurrence of bad influence upon the behavior of the actuator settled within the H/DA. In short, it has been found by the inventors that presently available FPC cables offer increased stiffness along the width and are thus incapable of being directly applied for use at narrow spaced locations.
It is estimated that the above-noted bad influence does not take place in the structure as disclosed in the JP-A-8-161880 because the use of its dedicated H/DA and the specially designed electronic control circuit board in combination permits achievement of any desired cable wiring and routing without suffering from limitations thereto. In other words, even where a cable is disposed in a narrow space defined within the fixed frame while being curved or folded at its one or several portions as shown in FIG. 23, the cable""s counterforce hardly affects the dedicated H/DA""s rotary support mechanism. The electronic control circuit board and the H/DA are separately attached in a way independent of each other; during this process, electrical connection between the HDA and the fixed frame did not affect the behavior of the actuator within the H/DA.
A currently available general purpose 3.5-inch form factor type H/DA and its associated electronic control circuit board for use in controlling this H/DA are typically integrated together while causing a connector for transmission of electrical signals toward the outside of the HDA to be directly secured to either one of the H/DA and the electronic control circuit board. In addition, the dimensions of the magnetic disk drive as a whole and the interface are designed to meet a prespecified specification (i.e. interface satisfying the existing standard, such as IDE, EIDE, SCSI, or the like). Due to this, when applying a general purpose HDA of after-market item to the architecture as disclosed in JP-A-8-161880 for achievement of further popularization, it should be required to avoid two problems which follow:
1) The use of an HDA of after-market item would result in that its connector restricts or limits the selectability of interface type while precluding free designing of connector position. To avoid this problem, careful consideration should be given to electrical connection between the HDA and a fixed frame having either terminals or a printed circuit board for access thereto. More practically, xe2x80x9cspecialxe2x80x9d system design activities are required to attain the intended routing of a cable for electrical interconnection.
2) The use of a known technique for fixation to the upper-level apparatus""s drive bay using screw holes as provided in a general purpose HDA results in the HDA being rigidly fastened to a fixed frame, which is insufficient in remedy for externally attendant vibration and shocks. To avoid this problem, an elastic or xe2x80x9csoftxe2x80x9d fixation technique must be applied without accompanying penalties, which technique is for achieving supportability with rotatability or with relative resiliency against spin motion and/or rotation shocks about a certain axis of rotation rather than translational external force being applied to the HDA, in a way as disclosed in JP-A-8-161880. It is also a must to design in such a way as to eliminate bad influence upon the soft fixation otherwise occurring due to cable routing while simultaneously leaving within the interior of a drive bay an extra space margin for accommodation of a soft fixation mechanism therein.
Here, the term rigid or xe2x80x9chardxe2x80x9d fixation is to be understood to mean the fixation based in principle on elastic deformation of metals for engagement togetherxe2x80x94for instance, securing a target body to a metallic member using metal screws with metal washers intervening therebetween during screwing. In this respect, it should be understood that the hard fixation is also established even when the member used is partly made of hard materials other than metals, such as glass or ceramic material.
On the contrary, the soft fixation as used herein may refer to a technique for securing an object by screwing with use of elastic washers and/or resilient members as disposed adjacent to screw holes, or alternatively a structure for rotatably or relatively resiliently supporting an object with respect to rotary motion and/or spin shocks about a certain axis of rotation.
It is therefore an object of the present invention to provide a support mechanism for use with an HDA of a general purpose product capable of retaining resistivities against vibration and impact shocks of prior art RAID systems and large size magnetic disk apparatus while at the same time reducing production costs thereof.
It is another object of this invention to provide an HDA support mechanism capable of improving vibration/shock resistivities of electronic equipment mounting therein an HDA without lowering the accuracy of position alignment of a magnetic head within an H/DA and also without requiring any physical and electrical alternations to such electronic equipment.
It is a further object of the invention to apply the technique as disclosed in JP-A-8-161880 while employing an HDA of general-use product without degrading the positioning accuracy of a magnetic head within its H/DA and also without requiring physical and electrical alternations to electronic equipment mounting the HDA therein.
A specific structure is provided for use in disposing a curved portion of a cable for transmission of electrical signals from an HDA of commercially available general-use product, which portion can affect rotation of a rotatably supported HDA, in such a manner as to be identical with the position of the center of gravity of the HDA (in other words, a position of the rotation center) while letting either HDA or H/DA be attached to a fixed frame so that it is rotatable about the center of gravity thereof. Disposing is done in a way such that provision of a marginal space between a cable and the fixed frame precludes creation of counterforce occurring due to friction between the cable and fixed frame. In addition, through special designing of the shape of a cable for use in transferring electrical signals from the HDA of general-use product, the cable is routed or xe2x80x9crailedxe2x80x9d to preclude occurrence of bad influence in a support system of soft fixation of the HDA. Further, the HDA is soft-secured to the fixed frame, which in turn is mounted into a drive bay of the electronic equipment. This results in achievement of an advantage that the magnetic head settling characteristics are no longer degraded. Additionally a magnetic disk device of the narrow sense as mounted in the electronic equipment is improved in anti-vibration characteristics.
It is permissible that the cable""s curved portion is spaced apart from the H/DA""s gravity center as long as degradation of settling characteristics is within an allowable range; alternatively, the cable may be modified to be variable in shape. It will also be permissible that when soft-securing the HDA to the fixed frame, a magnetic disk device less in size than those magnetic disk devices (narrow sense) with specification standards adaptable for the drive bay of interest is used to reserve an extra space for use in providing a soft securing mechanism. The cable may include a bundle of multiple signal transmission wires such as flexible printed circuit (FPC) cable or flat cables or else.
More specifically, at least two pairs of link mechanisms or plate members are provided for support between the HDA (including an electronic control circuit board and H/DA) and a fixed frame while causing hinges of them to be laid out along a line segment passing through the center of gravity of such HDA. A relation of this gravity center and the line segment may be determined with accuracies slightly deviated from the exact accuracy of assembling the HDA into the fixed frame. Where the mass of a holder supporting the HDA is not negligible relative to the mass of HDA, the position of the gravity center of certain part including the holder should be taken into consideration. And, let a cable as extended from the HDA be disposed so that its curved portion is identical to the HDA""s gravity center. An extra space is defined between the cable extended from the HDA and its associative fixed frame to thereby preclude unwanted inhibition of movement due to soft fixation of the HDA. Additionally the cable extended from the HDA is formed into a crank-like shape with two bent portions at right angles, rather than a straight parallel line. Alternatively, a structure is employable which forms the cable extended from the HDA into a straight parallel line which is bent at more than two portions for wiring.
In case the drive bay of the electronic equipment of interest is inherently designed for installation of a 3.5-inch magnetic disk drive unit, a 2.5-inch magnetic disk drive of commercially available general purpose product is soft-secured to a 3.5-inch type fixed frame; then, the above-stated or later-discussed cable wiring is to be done while retaining a spatial margin for provision of a soft fixation mechanism therein.
Preferably the cable as used herein may be a FPC cable with good temperature characteristics and durability against repeated physical deformation. It is also permissible that electrical signals from the HDA are sent forth to a supervisory or xe2x80x9cupper levelxe2x80x9d apparatus via a drive interface conversion substrate or board.
It should be noted that the drive interface conversion board is an electronic circuit board that is required for conversion of a xe2x80x9cnativexe2x80x9d type of interface into a desired interface in view of the fact that in those magnetic disk devices of narrow sense which are commercially available as general-use products or xe2x80x9cafter-marketxe2x80x9d items, the kind of interface is automatically determined depending on the type of connectors and/or commercially available general-use products (magnetic disk devices of narrow sense) per se. Even where such interface conversion is unnecessary, it is inevitable that the cable is extended outwardly from the HDA, which would result in the cable being secured to a specified portion of the fixed frame or other similar housing partsxe2x80x94in view of this, it is important to dispose while taking account of specific viewpoints which follow: The cable is disposed while causing its curved portion to be identical to the center of gravity of the HDA (rotation center); and the cable is hardly brought into contact with the fixed frame to thereby ensure that the counterforce of such cable does not badly affect the support system of soft fixation.
As a result, it becomes possible to suppress decrease in magnetic head positioning accuracy otherwise occurring due to unwanted vibrations of the support system of the cable. The vibrations discussed herein include vibration occurred when an actuator within the H/DA undergoes seeking and also vibration as externally applied theretoxe2x80x94in either case, the present invention offers the intended effects and advantages. Applying this invention makes it possible to install or constitute magnetic disk apparatus of the broad sense capable of exhibiting increased resistivities against vibrations and shocks, which in turn enables improvement in anti-vibration characteristics of electronic equipment concerned.